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Title: Uncertainty Quantification of NEPTUN Analysis Using Wilks's Formula With an Extended Number of Calculations

Abstract

The two-phase system analysis code MARS [1] has been used for the uncertainty quantification of NEPTUN reflood test [2] analysis. By performing 10,000 calculations based on a random variation of the MARS model parameters and measured data, a mean value, and the 95% upper bounds are traced along the number of calculations. The CPU-intensive calculations were performed using the 11 node PC-cluster under Linux platform. The Monte-Carlo calculation results suggest a total number of 2,000 calculations would be sufficient to determine the stable mean and 95% upper bound values. The peak temperatures predictions are also used to find the 95% bounding values by using the Wilks' method. For the 1. order one-sided formula, every 59 peak temperatures are examined to locate the bounding temperature, with a 95% confidence. The 2. and 3. order values were found in a similar way. The uncertainty band by the Wilks' formula, when compared with the true 95% bounding value, is observed to be quite broad, especially in the case of the 1. order. The 2. or 3. orders or a full Monte-Carlo method would be necessary to demonstrate that the safety of the plant is ensured with a sufficient margin. A supplementary sensitivity study,more » for the nine uncertain parameters selected for the NEPTUN analysis, is also performed to find the degree of influence of each parameter on the peak rod temperature. (authors)« less

Authors:
; ;  [1]
  1. Korea Atomic Energy Research Institute, P.O. Box 7, Daedok Science Town, Daejun 302-353 (Korea, Republic of)
Publication Date:
Research Org.:
The ASME Foundation, Inc., Three Park Avenue, New York, NY 10016-5990 (United States)
OSTI Identifier:
20997085
Resource Type:
Conference
Resource Relation:
Conference: 14. International conference on nuclear engineering (ICONE 14), Miami - Florida (United States), 17-20 Jul 2006; Other Information: Country of input: France
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; FORECASTING; M CODES; MONTE CARLO METHOD; PEAKS; RANDOMNESS; SAFETY; SENSITIVITY ANALYSIS; SYSTEMS ANALYSIS; TWO-PHASE FLOW

Citation Formats

Hwang, Moonkyu, Lee, Yong-Jin, and Chung, Bub-Dong. Uncertainty Quantification of NEPTUN Analysis Using Wilks's Formula With an Extended Number of Calculations. United States: N. p., 2006. Web.
Hwang, Moonkyu, Lee, Yong-Jin, & Chung, Bub-Dong. Uncertainty Quantification of NEPTUN Analysis Using Wilks's Formula With an Extended Number of Calculations. United States.
Hwang, Moonkyu, Lee, Yong-Jin, and Chung, Bub-Dong. Sat . "Uncertainty Quantification of NEPTUN Analysis Using Wilks's Formula With an Extended Number of Calculations". United States.
@article{osti_20997085,
title = {Uncertainty Quantification of NEPTUN Analysis Using Wilks's Formula With an Extended Number of Calculations},
author = {Hwang, Moonkyu and Lee, Yong-Jin and Chung, Bub-Dong},
abstractNote = {The two-phase system analysis code MARS [1] has been used for the uncertainty quantification of NEPTUN reflood test [2] analysis. By performing 10,000 calculations based on a random variation of the MARS model parameters and measured data, a mean value, and the 95% upper bounds are traced along the number of calculations. The CPU-intensive calculations were performed using the 11 node PC-cluster under Linux platform. The Monte-Carlo calculation results suggest a total number of 2,000 calculations would be sufficient to determine the stable mean and 95% upper bound values. The peak temperatures predictions are also used to find the 95% bounding values by using the Wilks' method. For the 1. order one-sided formula, every 59 peak temperatures are examined to locate the bounding temperature, with a 95% confidence. The 2. and 3. order values were found in a similar way. The uncertainty band by the Wilks' formula, when compared with the true 95% bounding value, is observed to be quite broad, especially in the case of the 1. order. The 2. or 3. orders or a full Monte-Carlo method would be necessary to demonstrate that the safety of the plant is ensured with a sufficient margin. A supplementary sensitivity study, for the nine uncertain parameters selected for the NEPTUN analysis, is also performed to find the degree of influence of each parameter on the peak rod temperature. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2006},
month = {7}
}

Conference:
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